Testing a toxic agent alarm with a nontoxic simulant

ABSTRACT

A method of using a material having no significant toxicity as a simulant to challenge the V and G toxic agent alarm to insure alarm sensitivity and function.

United States Patent [1 1 Epstein et al.

[451 Oct. 29, 1974 TESTING A TOXIC AGENT ALARM WITH A NONTOXIC SIMULANT Inventors: Joseph Epstein; Lewis M. Berkowitz,

both of Baltimore, Md.

Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

Filed: May 24, 1972 Appl. No.: 256,514

US. Cl. 204/1 T, 23/230 R, 73/1 R,

252/408, 340/237 R Int. Cl B0lk 1/00 Field of Search 23/230, 232; 252/408;

References Cited UNITED STATES PATENTS 12/1958 Roth 204/1 T Primary Examiner-Carl D. Quarforth Assistant Examiner-E. A. Miller Attorney, Agent, or Firm-Eugene E. Stevens; Theodore Major ABSTRACT A method of using a material having no significant toxicity as a simulant to challenge the V and G toxic agent alarm to insure alarm sensitivity and function.

4 Claims, N0 Drawings TESTING A TOXIC AGENT ALARM WITH A NONTOXIC SIMULANT DEDICATORY CLAUSE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

Our invention relates to a method of using a material In having no significant toxicity as a simulant to challenge the V and G toxic agent alarm, such as disclosed in US. Pat. application Ser. No. 768,560 filed on Oct. 16, 1968, to insure the sensitivity and function of the alarm.

Due to the dissemination of toxic compounds such as hydrogen cyanide, hydrogen sulfide, and chemical warfare agents in the atmosphere in industrial plants having hazardous atmospheres and in warfare, techniques and apparatus were necessary to monitor the existence of low concentration, such as 0.2 X to 0.4 X 10 grams of contaminant toxic compound per literof air, hazardous air contaminants. To satisfy the need for the above mentioned technique and apparatus, the device as disclosed in the aforementioned US. Pat. application Ser. No. 768,56O was conceived and reduced to practice. Upon conception and reduction to practice of the device disclosed in the aforementioned patent application, the problem arose as to how to insure reli-v ability of function and sensitivity ofthe device by using a material having nosignificant toxicity as a simulant and which would nevertheless mimic the toxic V and G agents, such as disclosed in US. Pat. Nos. 2,926,072 and 2,929,79l,'and challenge the alarm. Our invention was conceived and reduced to practice to satisfy the need for a material having no significant toxicity to ll ll function as the aforementioned simulant and to solve the aforementioned simulant problem.

A principal object of our invention is to provide a method whereby a toxic V and G agent alarm can be 5 challenged by a material which has no significant toxicity but which mimics the V and G agents to insure reliability of function and sensitivity of the alarm.

Other objects of our invention will be obvious from the specification hereinafter set forth.

Our invention will now be described in detail as follows.

The electrochemical cell and methodology, as disclosed in foregoing US. Pat. application Ser. No.

v768,560, has been standardized as a method and means to monitor the presence of V and G agents. The electrochemical method and means is based on the capability of a silver electrode to detect submicrogram quantities of the cyanide ion. G agents absorbed into the cell electrolyte are detected through a direct reaction with an oxime which results in the rapid formation of cyameans of chemical reaction with an impregnate in a conversion prefilter. G agents react with an oxime, such as isonitrosobenzoyl acetone. to liberate the cya nide ion and produce the Ag+2CN" Ag(CN) electrochemical reaction at the silver electrode. Each 30 decade change in cyanide ion concentration in the alarm cell electrolyte produces a MW change in potential which enables G and V agent detection and quantitative estimation. G agent analogues are detected in the same manner as described for the G agent.

35 The mechanics of the oxime reaction are as follows.

l. Formation of the oxime anion ll ll Q C CHBWO 2. o-phosphorylation of the oxime anion 3. Rapid cleavage of the oxime phosphonate ll. tl "O --c @c g c H oa, +CN+H O+CH C00 'in the conversion filter to convert V agent to G analogues, such as phosphonofluoridates, to react with the oxime; G agent not being reactable with the chemical composition of the conversion filter. While not a part of this invention, the process of impregnating the conversion filter is as follows. 1

The impregnation solution must be made immediately prior to use and cannot be stored, and the solution should'b'e mixed and'use'd only in polyethylene or polypropylene vessels. 187.5 t 0.2 g of silver nitrate are dissolved in 400 i 5 ml of deionized or distilled water, and 125.0 0.1 g of potassium fluoride are dissolved in a separate container in 440 i 5 ml of deionized or distilled water. While stirring the potassium fluoride solution, slowly add the solution of silver nitrate. The resulting mixture of'the two solutions will contain a turbid, tan suspended precipitate which is then filtered using a single sheet of Whatman No. 42 filter paper. The filtrate is retained and the precipitate discarded. While stirring the filtrate, 125 i 5 ml of absolute ethyl alcohol are added. A muddy, brown precipitate forms in suspension and should not be filtered out, because the precipitate will disappear and the liquid will clear as the below referenced dewaterproofed paper is imh pregnated. Pour approximately 965 ml of the impregnating liquid into a 7 /2 by 12 inch polyethylene tray. lmpre gnate one sheet of dewaterproofed type 5 paper at a time by completely immersing the sheet, removing all trapped air bubbles, and soaking the paper for to seconds. Remove the paper from the impregnating solution and drain excess liquid back into the tray. White or gray spots on the paper indicate incomplete dewaterproofing or contamination, and paper with this indication should be discarded. Sheets of impregnated paper are placed on polyethylene-covered glass plates and dried, in a preheated oven at 120 i 5F for l 1 1 hour. lmpregnated paper should be placed in the oven within five minutes after impregnation. After drying, the sheets are removed from the oven, cut into a size and shape suitable for a given application, and stored immediately in opaque polyethylene containers at arelative humidity ofless than 35 percent. Processed filters are not to be stored over or with silica gel or at relative humidities above 35 percent to avoid degradation of conversion efficiency.

In order to solve the above referenced simulant problem, it was necessary to conduct a research program to 7 develop a material which mimicked V agent in terms of chemical reaction with the conversion filter impregnate and chemical reaction with the oxime and nevertheless possessed no significant toxicity. The toxicity of the V agent is ascribed to two factors; namely. a high affinity for the enzyme cholinesterase and an easy release of the leaving group in the V molecule. High affinity for the enzyme cholinesterase is due to the presence of-a tertiary amine which at physiological pH is protonated; whereas the easy release of the leaving group is correlated with the basicity of the leaving ion, increase of the acidity of the anion resulting in more rapid departure.

' In view of the foregoing toxicity factors, research effort for a material to solve the aforementioned simulant problem was directed along lines to delete the portion of the molecule responsible for the affinity for the enzyme while at the same time increasing the basicity of the leaving group and not significantly altering the basic structure responsible for chemical reactivity.

During the course of research, it was unexpectedly found that the above simulant problem was solved by chemical compounds having the generic structure C H O s-R Wherein R is any alkyl group having C to C inclusive.

The preferred compound of our invention is O,S diethyl methylthiophosphonate which has a boiling point of 44 C at 0.3 mm, has a saturation vapor content of approximately 1.5mg/liter at 25C, has an activity toward bovine erythrocyte cholinesterase of approximately 1/10000 that of the V agent activity, produces a reproducible. immediate, and excellent response in the agent alarm to a concentration of 0.4;tg of simulant per liter of air. Our inventive simulant is prepared by 1. Distilled diethylmethyl phosphonite at 121/760 mm To 32.4 g (0.24 mole) diethylmethyl phosphonite at 3 C was added a mixture of 4.0 ml H 0 and 0.3 ml of HCl (4.3 g H O 0.24 mole H O). No reaction occured until the heterogeneous mixture was allowed to warm up to ca. 25 C. Temperature went up to ca. 75 C and mixture cleared up to a homogenous waterwhite liquid which was distilled. First fraction distilled at 3237/35 mm (probably starting material); second fraction distilled at 8892 C/35 mm lit bp 70/15 mm; K. A. Petrov, et al., Zhurnal Obschchei Khimii.,

31, 179 (1961). Yield of second fraction 20.4 g.

2. C. Borecki, et al., J. Chem. Soc., 4081 (1958) Ethyl methylphosphinate (20.4 g, 0.19 mole) was added to a solution of 40 g (0.17 mole) sodium in ca ml ethanol with no apparent reaction. To the clear solution, half gram portions of sulfur were added. a]- lowing the added sulfur to dissolve before any more was added. The temperature was kept between 10 and 17 with an ice bath. After 5.] g sulfur was added, no more sulfur dissolved. The mixture was allowed to warm to room temperature with stirring. After standing overnight at room temperature, a small amount of sulfur (0.5 g) was filtered off; the total amount of sulfur used was 4.6 g (0.14 mole). The filtrate was evaporated to dryness in vacuo to leave a white hygroscopic solid; it was ground under ether, dried in a desiccator and bottled under anhydrous conditions using a glove-bag. The best sample had a mp 200-205 C (decomposition with evolution of a gas).

We claim:

I. A method of testing or challenging an alarm for the detection of toxic G and V agents by using a simulant compound which has no significant toxicity, said alarm including an electrochemical cell with a silver electrode for the detection of CNions, said cell having an electrolyte including an oxime for reaction with phosphonofluoridates or G agents or analogs, whereby CNions are generated, said alarm further including -AgNO;, and KF for the conversion of V agents to G analogs, comprising the steps of providing an air sample containing said simulant compound having the formula W V CpHL wherein vR is any C through C alkyl group, reacting said compound of the air sample with the AgNQ, and KF to produce the corresponding fluoridate, passing said fluoridate to the electrochemical cell and reacting said fluoridate with the oxime in the electrolyte of the electrochemical cell of the alarm to produce CNions in the cell electrolyte, reacting the CNions at the silver electrode of the electrochemical cell to produce a change in potential, and monitoring the change in potential to determine the alarm challenge.

2. The method of claim 1 wherein R is C H I 3. The method of claim 2 wherein the simulant compound has a boiling point of 44C at 0.3 mm and a saturation vapor content of approximately l.5 mg/liter at 25C.

4. The method of claim 1 wherein the simulant compound concentration is 0.4 g/liter of air.

l l l =l 

1. A METHOD OF TESTING OR CHALLENGING AN ALARM FOR THE DETECTION OF TOXIC G AND V AGENTS BY USING A SIMULANT COMPOUND WHICH HAS NO SIGNIFICANT TOXICITY, SAID ALARM INCLUDING AN ELECTROCHEMICAL CELL WITH A SILVER ELCTRODE FOR THE DETECTION OF CN$IONS ARE GENERATED, SAID ALARM FURTHER OXIME FOR REACTION WITH PHOSPHONOFLUORIDATES OR G AGENTS OR ANALOGS, WHEREBY CN-IONS ARE GENERATED, SAID ALARM FURTHER INCLUDING AGNO3 AND KF FOR THE CONVERSION OF V AGENTS TO G ANALOGS, COMPRISING THE STEPS OF PROVIDING AN AIR SAMPLE CONTAINING SAID SIMULANT COMPOUND HAVING THE FORMULA
 2. The method of claim 1 wherein R is C2H5.
 3. The method of claim 2 wherein the simulant compound has a boiling point of 44*C at 0.3 mm and a saturation vapor content of approximately 1.5 mg/liter at 25*C.
 4. The method of claim 1 wherein the simulant compound concentration is 0.4 g/liter of air. 